Hotbox alarm



United States Patent HOTBOX ALARM Konrad F. Schreier, Jr., Los Angeles, and Norman L.

McCracken, Lafayette, Calif., assignors to Farr Company, El Segundo, Calif., a corporation of California Filed Nov. 24, 1967, Ser. No. 685,346 Int. Cl. B61k 9/04; G01k N02 US. Cl. 116114.5 10 Claims ABSTRACT OF THE DISCLOSURE An indicating device to warn of an overheating condition in a hearing which if allowed to continue would cause failure of a railway car axle or the like. The indicating device comprises a can containing a smoke producing chemical mounted on the end of the axle or rotating member. A large hole in the can axial to the rotating member is sealed with a cover attached by controlled melting point solder which releases the cover upon a rise in temperature to permit the emission of the can contents prior to journal failure. The centrifugal force of the rotating member and can causes the warning agent to remain in the can and to volatize in a controlled manner within the can thus giving a continuous indication for a period of time rather than discharging in one quick burst.

BACKGROUND OF THE INVENTION In the past, hotbox indicators of the smoke and/ or odorproducing type have been mounted either in the journal box casting or in the oil bath where liquid lubricant was placed.

For a number of years, these devices were satisfactory. However, in recent years, the greater speeds of trains and the resultant increased danger to lives and property from a journal failure have caused the railroads to condemn any journal which has been subjected to sufficient heat to cause discernible discoloration of the metal.

Upon adoption of these condemnation rules, chemical hotbox indicators were made as temperature sensative as possible without risking their spurious operation on a car parked in the hot summer sun. It soon became evident that they invariably failed to respond until the journal had become fatally damaged.

The temperature rise in the occurrence of a hotbox takes place in a peculiar manner. The first indication of trouble is an abnormal temperature rise at the outer end of the journal, near the end flange. This temperature rise is in excess of that likely to be created by ambient conditions, but significantly below discoloration temperature. This localized temperature rise subsists at a relatively steady level for a substantial period of time, usually sufficient for the train to reach a spur track before the graual temperature increase of the inner end of the journal due to conduction through the journal triggers a relatively sudden heating of the inner end of the journal which reaches the discoloration point in a relatively short period of time. This period of time is usually too short for effective countermeasures, particularly in long trains moving at high speeds.

Presently known chemical indicators do not respond to the symptomatic early temperature rise because, if they are mounted in the journal housing, the conduction heat cannot reach them until after it has already reached the inner end of the journal and triggered the hotbox; and furthermore, such locations are adversely affected by ambient temperatures, particularly in winter.

The location in the lubricant bath is unsatisfactory because the bath at best reflects, after a certain time lag, the average temperature of the entire journal, and hence again does not reach a critical ratio unless it is too late.

3,520,274 Patented July 14, 1970 "ice Moreover, the previous forms of smoke and odorproducing warning devices, if they operated at all, would quickly discharge their indicating substance which often would go unnoticed.

SUMMARY OF THE INVENTION The present invention is directed to a novel form of device for warning of the overheating of a railroad car axle and consists of a canister containing smoke generating chemicals and adapted to be fastened to the end of the axle. The canister end adjacent to the end of the axle is sealed with a tinplate disc held in place with solder having a preselected melting point. As the axle temperature rises the chemical vapor pressure increases within the canister. When the temperature rises to the melting point of the solder, which is a temperature just below that causing a hazard to the bearing and journal, the solder melts and the vapor pressure dislodges the disc for the chemical smoke indicator to escape into the atmosphere. The disccovered hole in the canister is relatively large to avoid clogging with chemicals and yet is centrally located on the axis of rotation whereby the centrifugal force tends to retain the chemicals in the canister thereby producing a slowed but continuing rate of smoke discharge.

FIG. 1 is a cross sectional side elevation of a typical railroad car journal box with the hotbox alarm of this invention in place.

FIG. 2 is a fragmentary end elevation of the journal and hotbox alarm taken substantially along line 22 of FIG. 1.

FIG. 3 is an enlarged cross sectional side elevation of the hotbox alarm taken substantially along line 3--3 of FIG. 2.

FIG. 4 is a partial cross sectional elevation of the hotbox alarm taken substantially on the line 4-4 of FIG. 2 and illustrating the alarm in operation indicating overheating.

DETAILED DESCRIPTION In a preferred embodiment of the invention, FIG. 1 illustrates a portion of a railway car axle and Wheel, generally designated 10, and having a running surface 12. The axle and Wheel terminate in an end flange 16 which defines an outer end of the running surface 12 and is joined thereto by a curved shoulder 18. The weight of the car is transmitted by the journal support 20 through the intermediary of a supporting block 22 and a running block 24. Lubrication is customarily achieved by oil soaked lubricating pads located generally in the area designated as 26. The running surface 12 rubs against these pads while it is rotating.

The maximum temperature rise and failure of the journal in the event of a so-called hotbox occurs within the area immediately to the left of the rounded shoulder 19 at the inner end of the running surface 12. However, the occurrence of the destructive temperature rise at that point is preceded by a comparatively prolonged temperature rise in the area of the journal immediately adjacent the outer flange 16.

Therefore the hotbox alarm or indicator of this invention, designated generally as 1, is mounted on flange 16 by utilizing the centering hole 14 conventionally provided on end for machining the axle 10. The device 1 is fastened to the axle by means of an expansible insert or blind fastener 28 as shown in FIG. 3 and commonly known in the art.

Referring now to FIGS. 3 and 4, the container support plate 30 is bolted to the outer flange 16 of the journal by means of the blind fastener 28. This support is provided with retaining means 32 which for the purposes of illustration are shown as spring clips. These clips 32 hold a canister 34 in place against the plate 30. The canister has a domed or concave end 35 facing the plate and forming a chamber between the dome end and plate 30. A central opening in end 35 is covered by a disc 36 which may be formed of tinplate or the like. This disc 36 is soldered in place on that side of domed end 35 facing plate 30 with solder 41 which has a melting point at the desired alarm temperature.

The chemical 38 contained in the canister 34 is designed to emit smoke when the alarm is activated and may also contain odor producing substances for alarm purposes if desired. Among the chemicals 38 is carbon tetrachloride to generate gas pressure in the canister 34. When the end of the axle reaches a temperature sufficient to melt the solder 41, it has also generated enough gas pressure inside of the can to positively blow off the tin plate cover 36. One property of the eutectic solder is that there is no appreciable softening stage so that the release is virtually instantaneous when the prop er temperature is reached. The large hole in the center of the can produced by the blowing of the tinplate disc 36 prevents any plugging of the exit orifice formed by opening 40 (FIG. 4) with solids formed by interaction of the smoke-producing chemicals. The support plate 30 has a plurality (four shown) of notches -42 where the rim of the canister 34 engages the plate to allow the escape of the generated smoke. The centrifugal force induced by rotation causes the chemical materials in the canister 34 to be forced outwardly against the walls of the canister 34 as shown in FIG. 4 whereby the chemio cal reaction will occur and produce smoke from the inner surface without the chemicals passing out through the opening 40.

Although many chemicals may be satisfactory for use in this invention, we prefer using titanium tetrachloride and about 10% carbon tetrachloride filling the canister. Preferably the filling is accomplished through a small hole 43 with the disc 36 preassembled and then the hole 43 is sealed in any convenient manner. The reaction of the chemical with the moisture in the atmosphere forms a dense silver-gray smoke, readily visible to an observer in the caboose of the freight train. The specific chemical reaction is as follows:

TiCl +2H O4HCl+TiO wherein the HCl is in the form of a vapor which carries the silver-gray TiO The combination of the two results in an easily visible smoking lasting from 10 to 15 minutes.

This indicator may also be mixed with compatible odor-producing agents, specifically those of the mercaptan series, to call the observers attention to the fact that a hotbox indicator has been activated.

While the preferred embodiment of the invention has been described herein, the invention is not to be construed as limited to the specific details disclosed.

We claim:

1. A hotbox alarm for a railroad truck axle comprising: a canister adapted to be mounted on the end of the truck axle, said canister being at least partially filled with an indication-producing and gas pressure developing means; said canister having a large opening spaced radially inwardly from the periphery of said canister and a rigid member covering said opening and mounted on the exterior of said canister by means releasable at a predetermined safe temperature, said gas pressure developing means being responsive to any increase in pressure to forcibly discharge said member upon said mounting means reaching said predetermined safe temperature to emit the indication caused by the indication-producing means.

2. The hotbox alarm of claim 1 wherein said indicationproducing and gas pressure developing means include titanium tetrachloride and carbon tetrachloride to produce a visual indication of journal overheating and an odor producing agent to indicate activation of said alarm.

3. The hotbox alarm of claim 1 wherein said canister has an outer periphery radially spaced from the axis of the axle, said indication-producing and gas pressure developing means only partially fills said canister, and said large opening in the canister is spaced radially inwardly from said periphery.

4. A hotbox alarm for a railroad truck axle comprising:

a canister containing an indication-producing agent and mounted on the end of the truck axle, said canister having a large hole axially aligned with the axle, said hole sealed with a member by means adapted to be released at a predetermined safe temperature for permitting the emission of said indication-producing agent prior to journal failure from overheating, said indication-producing agent comprises carbon tetrachloride to generate gas pressure upon heating of said canister and titanium tetrachloride to react with the moisture in the atmosphere upon release of said member to form a dense silver-gray smoke prior to journal failure from overheating.

5. A hotbox alarm for a railroad truck axle comprising:

a canister containing an indication-producing agent and mounted on the end of the truck axle, said canister having a large hole axially aligned with the axle, said hole sealed with a member 'by means adapted to be released at a predetermined safe temperature for permitting the emission of said indication-producing agent prior to journal failure from overheating, said canister hole faces said axle and said support comprises a plate engaged by said canister with said plate having peripheral exit notches to allow indication produced by said agent to escape to the atmosphere at a controlled rate giving a continuous signal prior to journal failure from overheating.

6. A hotbox alarm for a railroad truck axle com prising:

a canister containing an indication-producing agent and mounted on the end of the truck axle, said canister having a large hole axially aligned with the axle, said hole sealed with a member by means adapted to be released at a predetermined safe temperature for permitting the emission of said indication-producing agent prior to journal failure from overheating, said canister being rotated by the axle, said rotation producing a centrifugal force which prevents the agent from freely flowing from the centrally located hole until said agent is sufficiently volatilized to produce said indication prior to journal failure from overheating.

7. A hotbox alarm for a railroad truck axle comprising:

a canister containing an indication-producing agent and mounted on the end of the truck axle, said canister having a large hole axially aligned with the axle, said hole sealed with a member by means adapted to be released at a predetermined safe temperature for permitting the emission of said indication-producing agent prior to journal failure from overheating, said indication-producing agent comprises carbon tetrachloride to generate gas pressure upon heating of said canister and titanium tetrachloride to re act with the moisture in the atmosphere upon release of said member to form a dense silver-gray smoke prior to journal failure from overheating, said means adapted to release said member comprises an eutectic solder and the combination of said gas pressure and the melting of the eutectic solder cause the opening of the member in a decisive manner to permit emission of the canisters contents prior to journal failure from overheating.

8. A hotbox alarm for a railroad truck axle comprising: a canister mounted on the end of the truck axle, said canister being at least partially filled with indicationproducing and gas pressure developing means, said canister having a large opening axially aligned with the truck axle, and a rigid member covering said opening and mounted on the exterior of said canister by means releasable at a predetermined safe temperature, said gas pressure developing means being responsive to any increase in pressure to forcibly discharge said member upon the mounting means reaching said predetermined safe temperature to emit the indication caused by the indication-producing means.

9. The hotbox alarm of claim 8 wherein said indication-producing and gas pressure developing means include titanium tetrachloride and carbon tetrachloride.

10. The hotbox alarm of claim 8 wherein said opening 6 provided between the canister and the axle for causing slow escape of the indication produced.

References Cited UNITED STATES PATENTS 2,203,051 6/1940 Green et a1. 116-1145 2,552,271 5/1951 Faus 246169 2,694,997 11/1954 Alger 246-169 10 ARTHUR L. LA POINT, Primary Examiner G. H. LIBMAN, Assistant Examiner US. Cl. XtR.

faces the truck axle and small peripheral openings are 5 246--169 

